This example presents a blank, interactive canvas as an SVG element that fills the entire browser viewport. The visualization consists of a single large rectangle with rounded corners, rendered in a default black color against the white page background. The SVG is sized dynamically to match the dimensions of the browser window using the client dimensions. The code relies on D3 version 5 to select the SVG element and append the rectangle, while CSS positioning ensures the canvas remains fixed to the viewport edges.